Reprogramming of mature smooth muscle cells to vascular progenitor cells

摘要 血管平滑肌细胞是一种特殊的细胞，表达收缩、静止的表型，但能够 正在经历重大的表型和功能变化。因此，成熟的中小企业是主要的贡献者 病理性血管重塑。值得注意的是，使用高度特定的SMC谱系映射方法，我们 在动脉外膜中检测到SMC来源的细胞，表明成熟的SMC对动脉内膜和 外膜重塑。最近发现正常的外膜是常住人口的家园 具有多种命运潜能的血管干/祖细胞提出了关于这些作用的新的重要问题 细胞在动脉壁的生长、重塑、修复和疾病中发挥作用。我们描述了一群外星人 表达前体细胞标记Sca1和CD34的血管前体细胞(AdvSca1细胞)并聚集在 刺猬信号的外围域。我们发表的工作展示了两个不同的亚群 AdvSca1细胞，一种来源于成熟的SMC的细胞，这些SMC经历了原位重新编程，并依赖于 转录因子KLF4的诱导。其他研究小组已经证明，在SMC中诱导KLF4可以促进SMC 动脉粥样硬化和癌症进展背景下的细胞转变，然而KLF4的机制 归纳法仍不清楚。我们还证明了SMC来源的AdvSca1细胞(AdvSca1-SM)表现出 能分化为多种细胞类型的多潜能表型。此外，我们还证明了AdvSca1- SM细胞对血管损伤的快速反应表明这些细胞是血管损伤的主要来源 损伤诱导的外膜重塑。AdvSca1-SM细胞在血管环境中的全功能能力 疾病仍然未知，这在很大程度上是因为缺乏可靠和特定的谱系测绘系统。我们的新产品 数据支持外星微环境对重新编程过程和 通过诱导结构性Gli1活性促进重新编程，后者诱导长的非编码RNA (LncRNA)H19，以及下游Wnt/β-catenin信号的激活。Wnt/β-连环蛋白活性驱动表达 多能性基因Myc和Klf4，导致SMC重新编程和AdvSca1-SM细胞维持 和宁静。作为对损伤的反应，AdvSca1-SM细胞下调Gli1/H19/Wnt/β-catenin/Klf4信号， 获得促纤维化的肌成纤维细胞表型，并且是血管纤维化的主要贡献者。相比之下， 成熟的SMC下调SMC标志物，并获得祖细胞表型。对于这个项目，我们建议 独特的外周微环境通过自主性和结构性促进SMC重编程 激活Gli1/H19/Wnt/β-连环蛋白信号转导通路(目的1)，失去Gli1/H19/Wnt/β-连环蛋白活性促进 血管损伤或血管形成中AdvSca1-SM向肌成纤维细胞分化与外膜纤维化 动脉粥样硬化背景下的扩张和斑块新生血管(目标二)，而动脉粥样硬化 斑块微环境通过类似途径促进SMC重编程以促进内膜SMC 和巨噬细胞聚集(目标三)。

ABSTRACT Vascular SMCs are specialized cells that express a contractile, quiescent phenotype, but are capable of undergoing significant phenotypic and functional alterations. As a result, mature SMCs are major contributors to pathological vascular remodeling. Using a highly specific SMC lineage-mapping approach, remarkably, we detected SMC-derived cells in the arterial adventitia, suggesting that mature SMCs contribute to both intimal and adventitial remodeling. The recent discovery that the normal adventitia is home to a resident population of vascular stem/progenitor cells with multiple fate potentials raised new and important questions about roles these cells play in growth, remodeling, repair, and disease of the artery wall. We described a population of adventitial vascular progenitor cells that express the progenitor cell markers Sca1 and CD34 (AdvSca1 cells) and cluster in an adventitial domain of hedgehog signaling. Our published work demonstrated two distinct subpopulations of AdvSca1 cells, one that derives from mature SMCs that undergo reprogramming in situ and is dependent on induction of the transcription factor, Klf4. Other groups have shown that induction of Klf4 in SMCs promotes SMC cell transitions in the setting in atherosclerosis and cancer progression, however the mechanism underlying Klf4 induction remains unknown. We also demonstrated that SMC-derived AdvSca1 cells (AdvSca1-SM) exhibit a multipotent phenotype capable of differentiating into multiple cell types. Further, we demonstrated that AdvSca1- SM cells expand rapidly in response to vascular injury suggesting that these cells are the dominant source of injury-induced adventitial remodeling. The full functional capacity of AdvSca1-SM cells in the setting of vascular disease remains unknown largely due to the lack of a reliable and specific lineage-mapping system. Our new data support the concept that the adventitial microenvironment is critical to the reprogramming process and promotes reprogramming through induction of constitutive Gli1 activity, which induces the long non-coding RNA (lncRNA) H19, and downstream activation of Wnt/β-catenin signaling. Wnt/β-catenin activity drives expression of the pluripotency genes, Myc and Klf4, resulting in SMC reprogramming and AdvSca1-SM cell maintenance and quiescence. In response to injury, AdvSca1-SM cells downregulate Gli1/H19/Wnt/β-catenin/Klf4 signaling, acquire a pro-fibrotic myofibroblast phenotype, and are the major contributors to vascular fibrosis. In contrast, mature SMCs downregulate SMC markers and acquire a progenitor cell phenotype. For this project, we propose that the unique adventitial microenvironment promotes SMC reprogramming by autonomous and constitutive activation of Gli1/H19/Wnt/β-catenin signaling (Aim One), that loss of Gli1/H19/Wnt/β-catenin activity promotes AdvSca1-SM-to-myofibroblast differentiation and adventitial fibrosis in the setting of injury or vasa vasorum expansion and plaque neovascularization in the setting of atherogenesis (Aim Two), and that the atherosclerotic plaque microenvironment promotes SMC reprogramming through a similar pathway to contribute to intimal SMC and macrophage accumulation (Aim Three).